export default function(coder: any) {

  coder['colour_picker'] = function(block: any) {
    // Colour picker.
    var code = '\'' + block.getFieldValue('COLOUR') + '\'';
    return [code, coder.ORDER_ATOMIC];
  };

  coder['colour_random'] = function(block: any) {
    // Generate a random colour.
    var functionName = coder.provideFunction_(
        'colourRandom',
        ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ + '() {',
          '  var num = Math.floor(Math.random() * Math.pow(2, 24));',
          '  return \'#\' + (\'00000\' + num.toString(16)).substr(-6);',
          '}']);
    var code = functionName + '()';
    return [code, coder.ORDER_FUNCTION_CALL];
  };

  coder['colour_rgb'] = function(block: any) {
    // Compose a colour from RGB components expressed as percentages.
    var red = coder.valueToCode(block, 'RED',
        coder.ORDER_COMMA) || 0;
    var green = coder.valueToCode(block, 'GREEN',
        coder.ORDER_COMMA) || 0;
    var blue = coder.valueToCode(block, 'BLUE',
        coder.ORDER_COMMA) || 0;
    var functionName = coder.provideFunction_(
        'colourRgb',
        ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
            '(r, g, b) {',
        '  r = Math.max(Math.min(Number(r), 100), 0) * 2.55;',
        '  g = Math.max(Math.min(Number(g), 100), 0) * 2.55;',
        '  b = Math.max(Math.min(Number(b), 100), 0) * 2.55;',
        '  r = (\'0\' + (Math.round(r) || 0).toString(16)).slice(-2);',
        '  g = (\'0\' + (Math.round(g) || 0).toString(16)).slice(-2);',
        '  b = (\'0\' + (Math.round(b) || 0).toString(16)).slice(-2);',
        '  return \'#\' + r + g + b;',
        '}']);
    var code = functionName + '(' + red + ', ' + green + ', ' + blue + ')';
    return [code, coder.ORDER_FUNCTION_CALL];
  };

  coder['colour_blend'] = function(block: any) {
    // Blend two colours together.
    var c1 = coder.valueToCode(block, 'COLOUR1',
        coder.ORDER_COMMA) || '\'#000000\'';
    var c2 = coder.valueToCode(block, 'COLOUR2',
        coder.ORDER_COMMA) || '\'#000000\'';
    var ratio = coder.valueToCode(block, 'RATIO',
        coder.ORDER_COMMA) || 0.5;
    var functionName = coder.provideFunction_(
        'colourBlend',
        ['function ' + coder.FUNCTION_NAME_PLACEHOLDER_ +
            '(c1, c2, ratio) {',
        '  ratio = Math.max(Math.min(Number(ratio), 1), 0);',
        '  var r1 = parseInt(c1.substring(1, 3), 16);',
        '  var g1 = parseInt(c1.substring(3, 5), 16);',
        '  var b1 = parseInt(c1.substring(5, 7), 16);',
        '  var r2 = parseInt(c2.substring(1, 3), 16);',
        '  var g2 = parseInt(c2.substring(3, 5), 16);',
        '  var b2 = parseInt(c2.substring(5, 7), 16);',
        '  var r = Math.round(r1 * (1 - ratio) + r2 * ratio);',
        '  var g = Math.round(g1 * (1 - ratio) + g2 * ratio);',
        '  var b = Math.round(b1 * (1 - ratio) + b2 * ratio);',
        '  r = (\'0\' + (r || 0).toString(16)).slice(-2);',
        '  g = (\'0\' + (g || 0).toString(16)).slice(-2);',
        '  b = (\'0\' + (b || 0).toString(16)).slice(-2);',
        '  return \'#\' + r + g + b;',
        '}']);
    var code = functionName + '(' + c1 + ', ' + c2 + ', ' + ratio + ')';
    return [code, coder.ORDER_FUNCTION_CALL];
  };
}